Heck, I never said they didn't, what I said was at the time of the CW they didn't. But it was also legal under the US Constitution. And yes, I can find ancestors that had slaves, but the few I can find were circa 1760 - 1820. The vast majority were farmers that employed their families or a hired hand. Slaves were way too expensive.
Most Northerners believe that all slaves were mistreated in the South. Propoganda & revisionist history. Why would the ex-slaves refuse to flee up north, and serve instead with their former owners? Why, when given the choice to leave, would the majority choose to sharecrop beside their former owner?
I have no doubt that the overwhelming majority of slave owners did not physically mistreak their slaves. The slaves were a valuable asset and formed a large part of the owners net worth. One would not intentionally harm something of that value. On the other hand, I wouldn't want that kind of life for myself and I doubt that anyone else would, either.